Question

Describe natural selection and give an example of natural selection at work in a population

Short answer

Natural selection is the process where advantageous traits increase in frequency within a population, as shown by the industrial melanism in peppered moths.

Step-by-step solution

Understand the Concept of Natural Selection

Natural selection is a process of evolution where organisms with traits that are better suited to their environment tend to survive and reproduce more than those with less advantageous traits. This process results in the gradual adaptation of a species to its environment over time.

Identify the Key Components of Natural Selection

Key components include variation, inheritance, selection, and time. **Variation** within a population allows for differences in traits. **Inheritance** means these traits can be passed to offspring. **Selection** favors the survival of individuals with advantageous traits. **Time** allows these traits to accumulate or increase in frequency within the population.

Describe an Example of Natural Selection

A classic example is the evolution of the peppered moth in England. Before the Industrial Revolution, most of these moths were light-colored, which helped them blend into the lichen-covered trees and avoid predators. However, after industrialization, soot covered the trees, and darker-colored moths had a survival advantage as they were better camouflaged.

Explain the Outcome of Natural Selection in the Example

Due to the color change in trees, the frequency of the dark-colored moths increased in the population over generations because they were less likely to be eaten by predators compared to their light-colored counterparts. This exemplifies natural selection as the moth population evolved to have a higher frequency of dark coloration, demonstrating adaptation to a changed environment.

Key concepts

Evolution

Evolution is the process by which species of organisms undergo gradual change over long periods of time. This concept hinges on genetic variation within populations. As these variations occur naturally, some traits become more common if they provide a survival or reproductive advantage. Evolution isn't something that happens overnight; it spans generations. But its impact can be seen in the slow transformation of species.

Natural selection is a key component of evolution. It "selects" traits that increase an organism's chances of survival and reproduction. Here are some important aspects of evolution through natural selection:

• Variation: The differences in traits among individuals in a population.
• Inheritance: The ability for traits to be passed from parents to offspring.
• Selection: The differential survival of individuals based on advantageous traits.
• Time: The process requires many generations for significant changes to become noticeable.

Over time, these factors work together, resulting in the evolution of species perfectly suited to their environment.

Adaptation

Adaptation refers to the process through which organisms become better suited to their habitat. This occurs as a result of natural selection, where advantageous traits are accumulated over generations. Adaptations can be structural, behavioral, or physiological, and they help organisms survive in specific environments.

Let's break down these types:

• Structural adaptations involve physical features such as a bird's beak shape suited for its food source.
• Behavioral adaptations refer to actions that enhance survival, like bird migration patterns.
• Physiological adaptations involve internal body processes, such as the ability of some animals to produce antifreeze proteins in cold environments.

These adaptations are not developed intentionally but are a consequence of the differential survival of the individuals with desirable traits. Over time, the traits that improve survival in an organism's habitat become more prevalent, thereby cementing their place in the population's genetic makeup.

Peppered Moth

The peppered moth is a textbook example of natural selection in action and exemplifies the process of adaptation. In the 19th-century England, the Industrial Revolution led to widespread pollution. This caused tree barks, initially pale and coated with lichen, to become darkened by soot. The color change of the environment initiated a selective pressure on the moth population.

Before industrialization, the light-colored peppered moths were predominant, as their coloration enabled camouflage against predators on the lichen-white trees. However, post-industrialization, the dark-colored moths, which were once rare, had an advantage. The sooty trees made it easier for these darker moths to blend in, reducing their chances of predation.

As a result, the population of peppered moths slowly shifted towards the darker variant, showing a classic instance of adaptation. This change didn't happen overnight but evolved over numerous generations, clearly demonstrating how environmental factors influence the frequency of traits in a population. This phenomenon is not just about shifts in color, but about how species are continuously adapting to their changing environments through natural selection.